Tomiyama Nariaki, Ikeda Ryuji, Nishizawa Yukihiko, Masuda Shogo, Tajitsu Yusuke, Takeda Yasuo
Department of Clinical Pharmacy and Pharmacology, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8520, Japan.
Department of Pharmacy, Izumi General Medical Center, Izumi-shi, Kagoshima 899-0131, Japan.
Oncol Lett. 2018 Jun;15(6):9929-9933. doi: 10.3892/ol.2018.8568. Epub 2018 Apr 25.
Cancer stem-like cells (CSCs), which possess the ability to self-renewal and are multipotent, are regarded as the cause of tumor formation, recurrence, metastasis and drug resistance. It is necessary to understand the properties of CSCs in order to treat them effectively. It has been previously reported that S100 family proteins, which carry calcium-binding EF-hand motifs and are associated with tumorigenic processes, serve crucial roles in maintaining cancer stem-like properties. S100A16 is upregulated in various types of cancer, including bladder, lung and pancreatic. However, the roles of S100A16 in cancer cells, particularly CSCs, are not clear. The present study investigated the roles of S100A16 in CSCs using the sphere formation assay of Yumoto cells, which are a human cervical carcinoma cell line. The mRNA expression levels were evaluated by reverse transcription-polymerase chain reaction and the protein expression levels were detected by western blot analysis. Following the sphere formation of Yumoto cells, the mRNA and protein expression level of Oct4, Nanog and S100A16 were increased compared with the control cells. Following transfection with S100A16 small interfering RNA (siRNA), the mRNA and protein expression of Oct4 and Nanog were decreased and the spheroid size was significantly decreased in the sphere formation of Yumoto cells compared with control siRNA treated cells. There was no change in the mRNA expression level, whereas the p53 protein expression level, which was decreased by the sphere formation, was recovered by S100A16 knockdown. In addition, the protein expression levels of Oct4 and Nanog, which were increased in the sphere formation, were decreased by the proteasome inhibitor lactacystin. No differences were observed in the S100A16 protein expression between the presence or absence of lactacystin. These results suggest that S100A16 serves an important role in the CSCs of human cervical carcinoma and is a positive regulator of Oct4 and Nanog.
癌症干细胞（CSCs）具有自我更新能力且具有多能性，被认为是肿瘤形成、复发、转移和耐药的原因。为了有效治疗癌症干细胞，有必要了解其特性。先前有报道称，携带钙结合EF-手基序且与致瘤过程相关的S100家族蛋白在维持癌症干细胞样特性中起关键作用。S100A16在包括膀胱癌、肺癌和胰腺癌在内的多种癌症中上调。然而，S100A16在癌细胞尤其是癌症干细胞中的作用尚不清楚。本研究使用人宫颈癌细胞系Yumoto细胞的成球试验研究了S100A16在癌症干细胞中的作用。通过逆转录-聚合酶链反应评估mRNA表达水平，通过蛋白质印迹分析检测蛋白质表达水平。Yumoto细胞成球后，与对照细胞相比，Oct4、Nanog和S100A16的mRNA和蛋白质表达水平升高。用S100A16小干扰RNA（siRNA）转染后，与对照siRNA处理的细胞相比，Yumoto细胞成球过程中Oct4和Nanog的mRNA和蛋白质表达降低，球体大小显著减小。mRNA表达水平没有变化，而因成球而降低的p53蛋白表达水平通过S100A16敲低得以恢复。此外，蛋白酶体抑制剂乳胞素降低了成球过程中升高的Oct4和Nanog的蛋白质表达水平。在有无乳胞素的情况下，未观察到S100A16蛋白表达的差异。这些结果表明，S100A16在人宫颈癌的癌症干细胞中起重要作用，是Oct4和Nanog的正调节因子。
